Helical bellows and method of making the same



July 28,1936. J, SIBAKE I 2,049,1m

HELICAL BELLOWS AND METHOD OF MAKING THE SAME Filed March 21, 1932 5Sheets-Sheet 1 July 28, 1936. J. s. BAKER 2,049,190

HELICAL BELLOWS AND METHOD OF MAKING THE SAME Filed March 21, 1932 l 5Sheets-Sheet 2 J. s. BAKER July 28, 1936.

HBLICAL BELLOWS AND METHOD OF MAKING THE SAME Filed March 21, 1932 5Sheets-Sheet 3 y 8,193s. J. s. BAKER 2.9m

HELICAL BELLOWS AND METHOD OF MAKING THE SAME Filed March 21, 1932 J5sheets-sheet 4 Jul 28, 1936. AK R 2,049,100

HELICAL BELLOWS AND METHOD OF MAKING THE SAME Filed March 21, 1952 5Sheets-Sheet 5 Wmfag X v/a/v/d' Patented July 28, 1936 2,049,100;nsuoar. BELLOWS AND METHOD or 0. THE SAME Application March 21, 1932,Serial No. 600,093 8 Claims. .(Cl. 113-120) The invention relates toflexiblebellows and methods of and apparatus ,for making the same.

Bellows may be divided mainly into two different types, 1. e., thecorrugated wall type formed from a tubularblank and the sectional plateassembly having individual plates mechanical y interlocked at theirperipheries. Both types are now applied to a great variety of uses whichrequire that they possess to a high degree the ,0 characteristics ofelasticity of form and uniformity of action, and also of greatdurability of performance, under repeated stress. In many uses to whichthey are put, a relatively large elastic range of movement is requiredto insure 5 that the wall shall return to its original form and length,without taking a permanent ,set, after the deforming force has beenremoved. The importance of this elasticity of form, as a whole, ascontrasted with the elastic limit of the metal, 0 becomes apparent whenit is remembered that the walls are frequently required to withstand avariation in axial length of twenty-five per cent, or even more, of thebellows length, whereas the metal of which they are ordinarily made mayhave an elastic limit of less than two per cent. Many I uses to whichthese devices are put require great endurance and life of the wallbecause it must withstand many millions of flexures without rupture.

The corrugated wall bellows made from a tubular blank is fabricated intoshape by subjecting the tube to various cold working operations, bymeans of which this tube is converted into the required corrugated form.Each time the blank 55 is subjected to a drawing operation which revduces the diameter of the same, and it is customary to subject theblankby small increments and thereby avoid imposing undue strain uponthe metal in its walls, a portion of the" end of the blank is workedover into the tubular wall. As the entire tubular wall is subjected tocold working during each drawing operation, it follows that the tubularwall is composed of a plurality of zones, each of which is subjected toone less the bottom up, and consequently, the metal wall lackinguniformity in its physical characteristics is no stronger than itsweakest zone. This method of working the metal to convert it into therequired corrugated form from atubular blank and 6 crease its elasticityand insure that it will return to its original form or length, withouttaking a permanent set, after the deforming force hasbeen removed.Annealing operations are not 20 necessary after the drawing operationsso that the problem of overcoming the presence of zones of differentphysical characteristics to obtain uniform flexibility and durabilitythroughout the wall is absent. Notwithstanding the superiority 25 ofthis type of bellows, the method employed heretofore to make thisproduct resulted in much waste of material, increasing in proportion tothe diameters of the plates, and expense in tooling for the varioussizes. 30

To overcome the above noted objections, and to secure the benefits of myinvention, I propose 'to employ a method of making flexible wallsobjects of the present invention is to provide a helically-shapedbellows having its flexible wall made of strip stock by cold workingoperations which increases the life or durability, as well as theresiliency of the finished wall and which provides for uniformity of themetal throughout so as to eliminate zones of different physicalcharacteristics. It is a further object of the invention to eliminatethe waste material necessary when sectional plates are iormed, which 5waste includes the inner portions and the outer corners cut away toshape the plates circular.

,A still further object of the invention is to increase the durabilityof the finished product, since the elimination of one of the seamsreduces the possibility of leaks by at least fifty P lt- Anotheradvantage of the present invention is ease with which strip stock may befabricated into helixes of different lengths and diameters withoutapparent sacrifice of strength or resiliency. The following are alsosome of the many advantages that may be obtained:

(A) Economy in use of material (strip stock).

(B) Economy in tooling for various sizes.

() Economy in production.

(D) Deeper flanges and a consequent greater expansibilityfor givenlengths of bellows.

(E) Use of any type of deep drawing material.

(F) Limited cold working of the metal and a consequent increasedhardness and durability.

- (G) Possible use of metal of greater hardness and a consequentincreased strength for the finished product.- I V i In order to apprisethose skilled in the art how to practice my invention, vI shall nowdescribe several preferred embodiments thereof in connection with theaccompanying drawings.

In the drawings: I

Figure 1 is a perspective view illustrating a machine for forming ahelical bellows from strip stock; I 1

-Fig. '2- is a detailed vertical sectional view of that portion of themachine-which feeds the strip stock under tension through the formingdevice Fig. 2 looking in the direction of the arrows;

Fig. 5' is an enlarged detailed sectional view 7 'of a portion ofseveral convolutions of the helix showing the manner in which thediefeeds the strip stock after formed cross-sectionally onto theconvolutions of the mandrel;

Fig. 6 is an edge view of a closure plate that may be used for the'endsof the helical bellcws;

Fig. 7 illustrates one way of securing this-end closure to the endconvolution of the bellows;

Fig. 8 illustrates the edges of adjacent con-. volutions in overlappingrelation, and also the manner of imbedding a reinforcing member therein;

Fig. 9 illustrates the overlapping edges of adjacent convolutions shapedsomewhat different- 1y to permit welding in order to secure amechanically tight, and, if so desired, a hermetically sealed joint;

Fig; 10 illustrates these overlapping edges formed somewhat differentlyto secure a diflerent 'form of joint;

Figs. 11 to 14, inclusive, illustrate different forms of end closureswhich may be used, in-

cluding .the plate shown in Fig.6; a

Figs. 15 and 16 illustrate thediiferent constructions which may be usedtofeed the strip to illustrate the manner of attaching an end platethereto.

- of flange desired, which may be a U or V, as

shown in the drawings, or other desirable form, and finally fed to amandrel to form a helix.

These steps may be varied somewhat in practice. I preferably provide thestrip stock I on a spool 2 suitably supported upon a shaft 3 carried bybearings 4 in the upper end of a rigid frame including the side angleirons 6 and I and a cross bar 8, supported upon and movable with a lathetool block 9.- Whileit is not essential broadly to keep strip stock Iunder tension as -it' is fed to the mandrel to form a helix, it ispreferable, and consequently, the strip stock i is formedcross-sectionally while imder tension,

' and then is fed to the continuous helical thread ill of mandrel II inthis shape. Limited cold working of metal does not detrimentally affectthe physical characteristics so as to produce brittleness in the metal,but, on the'contrary, beneficially increases the hardness or elasticityso that the finished product may have greater expansion without taking apermanent set.

Placing strip stock I under tension and shaping it cross-sectionally andslightly drawing the metal as it is fed to' the helical thread Iincreases, I have found, this desirable hardness without producing anydetrimental change of physical characteristics, the drawing placing themetal under tension and producing what may be termed "spring metal.

The metal is fed downwardly between guide guides l2 and I3, holds stripstock in positio as it is fed downwardly therebetween.

As shown in the drawings, a helically shaped bellows may consist of acontinuous helical flange 24 having edges of adjoining convolutionsoverlapping. Fonhing die plate I6 serves cross-sectionally to shape themetal strip l into this flange 24 before it is fed to the helical threadID of mandrel II. It is provided with a limited fiat surface l8 at itsupper end, over which the metal stock first travels and ridge is (seeFigs 1 to 4, inclusive), increasing in height and width, beginning atthe base of this fiat surface It and continuing to the lower end of thedie plate. The taper .of ridge I9 is gradual so that as the strip stockI passes thereover, it will be gradually shaped crosss'ectionally toassume the shape of flange 24.

Ridge I9 is shown slightly extended at the point engaged by die tool 20,as shown in Figs. 2 and 3, but it protrudes considerably at the point ofdie tool 2|, as shown in Figs; 2 and 4. These cooperating die tools and-2l act to confine metal strip I undertensio'n against this ridge IQ ofdie It, and also to complete the drawing operation of the metal into itsfinal cross-sectional .form. The metal is first folded over the peak ofridge [2, as shown in Fig. 3, and the side edges are brought together toform opposite walls 22 spec, o

peak of ridge it determines the form given tothe flange between walls 22and 28. Ridge is maybe of u formation, as shown in Fig. 4, or of vformation to form a V-shaped flange 25, as shown in Figs. 11 to 14,inclusive, or any other desired formation. Die plate it is provided withsub.- stantial side walls 32 and 33 throughout its entire length. Dietool 26 is provided with cooperating walls 26 and 21, which are boltedto walls 32 and 33 of the die plate. Die tool 2| is pro-- vided withsurfaces 28 and 29 on opposite sides. to cooperate with walls 32 and 33of the die plate. Screws maybe used to secure this die tool 2| to dieplate I8.

Mandrel i i is connected to the lathe headstock (not shown) by a shaft3|, and turns therewith, winding the flange 25 into helical formation.Any type of device may be used to feed helical flange 24 from die plateIt to flange Id of mandrel carried by tool post 31, to move a distanceequal to the pitch of the helical thread ID on mandrel ll, upon eachrevolution of said mandrel. The manner in which this is accomplishedwill be understood by those skilled in the art.

It is preferable to provide a substantial superstructure, including theangle iron posts 6 and I, upon lathe tool block 9 in view of the factthat the metal is pulled by a downward, counterclockwise motion ofmandrel H as it rotates. A brake 39 cooperating with spool 2 is alsoprovided to place metal stock I under tension- A suitable adjustingmember 40' may be provided for the brake to control the amount oftension on the strip stock. If so desirable, reinforcing frame members8| and 62 may be furnished for the angle irons 6 and I. The starting endof metal strip 1, designated 43 in Fig. 1, may be pulled over the dieplate i6 and through the die tools 29 and 21, and also through the die38. End t3 may then be locked by means of .a member at to the side ofthe mandrel adjacent to the forward end of helical mandrel thread 50.When mandrel ll is rotated in the. direction of the arrow, shownin Fig.1, the metal strip will be pulled tightly formation of flange 26 may.continue so that downwardly by the rotative force of this mandrel,while die 38 will act flrmly to feed helical flange 24 to and againstthe mandrel helical thread ID. The number'of turns or convolutions ofmandrel helical thread It need not necessarily determine the number ofconvolutions of the U'-flange 26 which any one bellows may comprise.After the mandrel is revolved a sumcient number of times to pull'flange24 over and upon its helical thread Iii, end 43 of flange zt'may bereleased from lock 44 and the flange freed from thread Iii and slippedforwardly to-rest-upon a rack 65 carried by the forward end of mandrelH, while the lathe tool block 9 may likewise be moved-to the right orstarting point on' the mandrel, whereupon the there need be no limit tothe number of convolutions flange 24 may be given to form one continuoushelical bellows. I have found that if the original set of convolutionsof flange 2d are freed from helical thread Ill and moved .to the rightupon the open frame 45, the continued helical formation of this flangeit may take place-these chanically interlocked by a combined folding andfirst convolutions riding upon frame 45 as it revolves-with mandrel H.

The manner in which the side edges of helical flange 24 may overlap isshown clearly in Fig. 5. This overlapping relation requires one of theco- 5 operating edges between adjacent convolutions to be smaller thanthe other to the extent of the thickness of the metal. Consequently,prong 48 of die 38 shaping inner edge 49 is provided slightly longerthan prong 50 shaping the outer edge El. 10 Edges 52 and 53 of thebellows shown in Fig. 8 are shown somewhat differently shaped from edges89 and 5! of the bellows shown in Fig. 5. The exact shape=of these edgesmay be very aptly controlled in the forming operation by the shape 16 ofprongs 68 and 50, forming dies i8, 28 and 2|, and the cooperatingsurfaces on the helical thread 10 of mandrel ll. Edges 52 and 53 are ofsuch depth as really to constitute flanges, but, for the purpose ofconsistency in this description, the 20 term edge will be maintained todescribe them.

If so desired,- a reinforcing member 54 may be inserted in the groove ofthe outer edge 53, as shown in Fig. 8, andthe walls 55 and 55 of theseedges may be crimped, as indicated generally at 25 51, to mechanicallylock this reinforcing member 54 in position. It is found desirable toprovide reinforcing member it somewhat resilient, al-

though this is not essential. After the crimping by the application ofsolder at the point 58 or 51 shown in Fig. 8. This soldering operationmay be carried out by placing the helical bellows on end, preferablyupon a rotating table, and applying the solder with an iron as thebellows rotates. 35 I find that carrying out this step. in this fashionresults in a veryuniform and substantial solder seal.

In Fig- 9, overlapping edges 60 and ti of adjacent convolutions areshown flat to permit theseedges to be welded in order to secure amechanically locked and hermetically sealed joint, if so desired,between convolutions.

-In Fig. 10, edges 62 and 63 are shown ruecrimping operation. 7

A novel form of plate or closure member has been provided for the endsof the bellows. These plates-or endclosures may be secured in differentways asshown in Figs. 11 to 14 inclusive. In Figs. 6, 7 and 18, I haveshown a substantially flat plate 60 having its outer edge portion shapedinto a helical flange Bi this edgev portion being cut at 82 in order toallow flange M to be threaded preferably into the end convolution of thebellows. As shown in detail in Fig. '7 and in elevation in Fig. 18,either edge 63 or 65 may be inserted in the open end, indicated at 65 inFig. 18, of'the end convolution of the helical flange M to permit thisflange an to be threaded into this last con- 69 volution, such threadingaction being easily ob= tained by rotating plate 60 until the oppositeedge isiiush with open end 65. Solder may be applied at open end 65 tohermetically seal the same, as indicated at 68 in Fig. '7 (this solderbeing broken 65 away at open end 65 in Fig. 18) and also about the upperedge at 80 to hermetically seal this end' of the bellows.

End plate '50 shown in Fig. 12 isprovided with 70 I the hermetical sealbetween end plate I and the bellows. In Fig. 13, the end plate Hi isprovided with an external annular flange T5. Solder is applied at 5 16while the open end 65 of the last convolution is brought against theadjoining convolution and soldered as at 11 to complete the hermeticalseal. In Fig. 14, end plate 18 is provided with a' radial flange 19,sometimes desirable in forming end connections for bellows. Thehermetical seal is provided in thesame manner as previously described.

Although I have illustrated a rotating mandrel having a helical threadthereon, and a rigid die 38 cooperating therewith, as a means of formingthe flange 24* into a helix, it will be understood that the stock metalI may be worked in other ways to secure this helical formation. Forinstance, in Fig. 15 I have illustrated a continuously 2Q travelingcaterpillar-like die 8i cooperating with a collapsible disk 82. Suitablemeans may be employed to feed the strip stock I to this die ill and disk-8.2- and to receive the same after passed therethrough. In Fig. 16 thecaterpillar die 8| is 25 3 shown cooperating with a fixed disk 83.

- Walls 55 and 56 of edges 52 and 53, as shown in Fig. 8, may be crimpedin any suitable way,

such as by the crimping jaws 85 and 86,- suitably held in operatingrelation by spring means 81 upon any suitable support. This crimpingoperation may be varied according to the type of joint desired.Consequently, I do not intend to be limited to any particular crimpingmethod or device to be used. From the foregoing description it will beapparent that the metal strip may be formed into a helix by firstforming a flange 24 and thereafter bringing this flange about a helicalthread upon a rotating mandrel. It will also be apparent that formingthe helix may be accomplished in various ways,- and I therefore do notintend to be limited to the exact details of performing-this formingoperation. I do not intend to be limited, on the other hand. to placingthe metal strip I I. under tension before forming the flange 24,although better results may be obtained so far as I know at the presenttime if this step is included in the method.

Without further elaboration, the foregoing will so fully explain thegist of my invention, that others may, by applying current knowledge,readily adopt the same for use under varying conditions of service,without eliminating certain features which may properly be said toconstitute 56 the essential items of novelty involved, which items areintended to be defined and secured to me by the following claims. -Iclaim:

i. A metallic bellows structure comprising .a continuous resilienthelically formed flange having hermetically sealed edges betweenadjacent convolutions and an end closure mechanically interlocked withone of the end convolutlons.

2. A metallic bellows structure comprising a ."continuous resilienthelical flange having hermetically sealed edges'between adjacentconvolutions and having an end plate provided with a helically formedcircumferential edge mechanically interlocked with one of the endconvolu- 7. tions of the helical flange. 3.A- metallic bellows structurecomprising a continuous resilient helical flange having hermeticallysealed edges between adjacent convolutions and having an end plateprovided with a helically formed circumferential edge'mechanicallyinterlocking with one of the convolutions of the helical flange, and ahermetical seal between said circumferential edge and said convolution.5 4. A metallic bellows structure comprising a continuous resilienthelical U flange, an end closure provided with a split helically formedcircumferential edge interlocking with the groove of one of the endconvolutions of said helical flange, 10 one end of said circumferentialsplit edge having been entered in said groove and moved therein untilthe opposite endthereof substantially ential edge on said end closureinterlocked with the end convolution of said helical U flange, saidcircumferential edge being split to provide for its 25 helical formationand interlocking relation with the groove of one of the endconvolutions, one of said split ends being inserted in said groove of.one of the end convolutions and said end enclosure being rotated untilthe opposite end of 30 said circumferential edge substantially enterssaid groove, and means for hermetically sealing said circumferentialedge and said end convolution. M 6. The method of making alongitudinally flexible metallic bellows which includes first placing astrip of spring metal under tension, then forming a relatively deepgroove in the strip while it is held under tension and conforming thesides thereof into flanges having preformed interlock- .40 ing edges,then helically coiling the strip after thus formed and overlapping thepreformed interlocking edges of adjacent convolutions in interlockingrelation, sealing said interlocking edges to provide a hermeticallysealed helically formed flanged wall, and flnally permanently attachingan end fitting to said wall by hermetically sealing said fitting to anend convolution.

7. 'The method of making a longitudinally flexible metallic bellowswhich includes tensioning a strip of spring metal, thereafter groovingthe tensioned strip to form side flanges having pre-' formedinterlocking edges, thereafter helically coiling the grooved tensionedstrip to bring said preformed interlocking edges of adjacentconvolutions in overlapping relation, and sealing said overlappedinterlocking edges to provide a hermetically sealed helically formedflanged wall.

8. The method of. making a longitudinally flexible metallic bellowswhich includes tensioning a strip of spring metal, thereafter groovingthe tensioned strip to form side flanges having preformed interlockingedges, thereafter helically coiling the grooved tensioned strip to bringsaid preformed interlocking edges of adjacent convolutions in overlappedrelation, the overlapped interlocking edges forming inward turned loopsof the helix, sealing the overlapped interlocking edges to provide ahermetically sealed helically formed flanged wall, and attaching afitting to at least the end convolution by a hermetically sealedrelation.

JOHN S. BAKER.

